The objective of this study is to investigate the relationship between home exposure to radon and lung cancer. This will be done through an analysis of 689 histologically confirmed cases of lung cancer and 744 age, sex and smoking matched controls. A similar case-control analysis will be conducted for 46 lung cancer cases among non-smokers, matched with 92 age and sex matched controls.The study will be conducted in five counties of Northwest New Jersey, a geographic area with one of the largest and most intense radon releasing formations in the United States. Year-long radon measurements will be made and house construction features evaluated in all the homes lived in by study subjects over the period 5 to 30 years prior to case or control subject identification. The relative risk of radon exposure will be calculated using both stratified techniques and regression analyses.Information on other cancer risk factors in the diet, environment and work of each study subject will be obtained and considered in the analyses.